It is well known that olefins such as ethylene, propylene, and 1-butene can be polymerized in the presence of certain metallic catalysts, a particular class includes the reaction products of certain organometallic compounds and transition metal compounds which can be used to form substantially linear polymers of relatively high molecular weight. Typically such polymerizations are carried out at relatively low temperatures and pressure.
It has been proposed to use certain organolanthanide compounds as olefin polymerization catalyst. Ballard et al in J. C. S. Chem. Comm., pages 994 and 995 (1978) reported that certain alkali bridged complexes of lanthanide metals such as [(C.sub.5 H.sub.5).sub.2 ErCH.sub.8 ].sub.2 and [(C.sub.5 H.sub.4 R).sub.2 YCH.sub.3 ].sub.2, would polymerize ethylene. In addition, Thompson and Bercaw in Pure and Applied Chemistry, Vol. 56, No. 1, pages 1-11 (1984), disclose that alkyl and hydride derivatives of permethylscandocene could polymerize ethylene. Although these catalysts were active in polymerizing ethylene, their activity was very short lived. Accordingly it was not possible to obtain particularly desirable levels of catalyst productivity using such catalysts.
An object of the present invention is to provide a novel yttrium compound consisting of the compound having the formula (Cp*.sub.2 YCl).sub.2, wherein Cp* stands for pentamethylcyclopentadiene.
Another object of the present invention is to provide a process for the polymerization of olefins using this novel dimeric yttrium compound.
Other aspects, objects, and advantages of the present invention will be apparent to those skilled in the art having the benefit of the present disclosure.